package com.example.market.util;

import java.security.MessageDigest;


public class MD5 {

    private static final String[] hexDigits = {"0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f"};

    /**
     * 字节转为16进制字符串
     * @param b 字节名
     * @return 16进制字符串
     */
    private static String byteToHexString(byte b) {
        int n = b;
        if (n < 0) n += 256;
        int d1 = n / 16;
        int d2 = n % 16;
        return hexDigits[d1] + hexDigits[d2];
    }

    /**
     * 字节数组转为16进制字符串
     * @param b 字节数组
     * @return 16进制字符串
     */
    private static String byteArrayToHexString(byte[] b) {
        StringBuilder resultSb = new StringBuilder();
        for (byte value : b) resultSb.append(byteToHexString(value));
        return resultSb.toString();
    }

    /**
     * 对字符串进行MD5加密
     * @param str 明文
     * @param charset 编码方式
     * @return 密文
     */
    public static String MD5Encode(String str, String charset) {
        String resultString = null;
        try {
            resultString = str;
            MessageDigest md = MessageDigest.getInstance("MD5");
            if (charset == null || charset.equals(""))
                resultString = byteArrayToHexString(md.digest(resultString.getBytes()));
            else
                resultString = byteArrayToHexString(md.digest(resultString.getBytes(charset)));
        } catch (Exception ignored) {}
        return resultString;
    }
}
